Toy building block



FIG. 1 is perspective view of a toy building block showing my new design;

FIG. 2 is a front elevational view thereof the side opposite being substantially identical;

FIG. 3 is a top plan view thereof the bottom plan view being substantially identical; and,

FIG. 4 is an end elevational view thereof, the end opposite being substantially identical. 

The ornamental design for a toy building block, as shown and described. 